United Nations officials said Friday they hope a cease-fire agreed by the Sudanese government and rebel groups operating in western Sudan will enable aid workers to reach people hit hard by the fighting there.

The head of the U.N. Office for the Coordination of Humanitarian Affairs in Khartoum, Ramesh Rajasingham, says, now that a cease-fire has been signed, his agency's first priority will be to visit the people of Darfur and assess their needs.

"We have a lot of populations we have not been able to see in north Darfur," he said. "Recently, there's been a lot of fighting in south Darfur. So, we would want to go and see what the population is like and what sort of condition they are in."

He calls on the Sudanese government to allow his agency and other aid workers unfettered and immediate access to as many as one million people affected by the war.

Government troops, rebels and an Arab militia many say is being backed by the government have been battling for more than a year, displacing an estimated 700,000 people, and killing an estimated 10,000.

On Thursday, in the Chadian capital Ndjamena, the Sudanese government and two rebel groups signed a renewable, 45-day cease-fire agreement that also guarantees aid workers safe access to Darfur.

Until now, aid workers have been complaining that the lack of security, combined with heavy government bureaucracy that made it almost impossible to get travel permits, have been hampering efforts to help civilians caught in the middle of fighting in Darfur.

But a spokesman for the U.N. Humanitarian Coordinator for Sudan, Ben Parker, says a successful cease-fire can go far in providing stability and security to the area. He says the biggest factor blocking aid workers from reaching many of the displaced people was lack of security.

"We hope that this cease-fire means that we can reach the two-thirds of the displaced people that currently we are not able to provide services to," he said.

Mr. Parker illustrates how security and stability will help the United Nations implement its planned campaign to immunize children in Darfur against measles.

"In the absence of a cease-fire, you are forced to go one place and do maybe 5,000, 10,000, 20,000 in one place, and then run to another, where you are hearing another measles outbreak, and you are constantly firefighting," he said. "In the context of a comprehensive cease-fire, we would be able to plan and execute a comprehensive, region-wide immunization, which would be far, far more effective and cost-efficient."

Mr. Parker says he is optimistic that the cease-fire will be successful, and calls it a massive, massive plus for Darfur.